//! Internal utilities shared across cache implementations.
//!
//! Nothing in this module is part of the public API.
use ;
/// Extension trait giving every cache a poison-tolerant `lock`.
///
/// A panic inside any operation that holds an inner `Mutex` poisons it.
/// The cache's invariants are not weakened by a poisoned lock — every
/// operation re-establishes consistency before returning — so we recover
/// the guard rather than propagating the poison upward as a user-visible
/// error.
pub